troy bilt pony

howdy all. I'm having a problem with my troy built Pony with a Kohler Courage 20HP engine. It was running fine and I shut it off (because I got stuck in the mud and had to push it out). Since then it won't start. I thought is may be the solenoid, so bypassed that, got a new spark plug and verified that I have spark. Last attempt was to try some starter fluid. the engine spins for a bit then backfires through the carb. Is there some issue with the timing? If so, how do I adjust it?

Any help would be appreciated.